Survival of infants with birth weights less than or equal to one thousand grams (ELBW) has increased from 17% in 1974 to 75% in 1994. Existing longitudinal studies of ELBW children have focused on relatively short-term cognitive and neuro-developmental outcomes. Much less is known about the long-term functional status of ELBW children beyond middle childhood and very few studies have examined growth and sexual maturation in relationship to functional outcome. This study will evaluate the growth, sexual maturation and the functional status of adolescents born with birth weights less than or equal to 1000 grams and will compare this to normal birth weight adolescents (NBW). The main hypothesis of this study is that assessment of the functional outcome of ELBW adolescents will reveal diminished capacity compared to NBW adolescents. These differences will be partially mediated by delays in growth and in sexual maturation in ELBW adolescents. The study population will include a cohort of 92 children without a major neuro-developmental disability (cerebral palsy, mental retardation IQ <70, blindness or deafness) enrolled in the neonatal intensive care follow-up program at UAB and who were born between 1978 and 1983. A comparison population of socio-demographically similar children of normal birth weight will be recruited. All participants will be assessed for growth using anthropometric measures (e.g. changes in z-scores) and development of skeletal mass and composition assessment (dual energy X-ray absorptiometry and bone age). Sexual maturation will be assessed using Tanner guidelines. Functional status will be evaluated using a global health status measure such as the Teen Health Profile. Cognitive, behavioral, and academic measures as well as self image inventories will also be included.